I have a kind of old Canon LIDE60 and I would not try to claim there's some fix-all for these problems, as I experience them myself and honestly the worst part is when you try to prevent one or two of these problems, it causes the other two. The grainy thing is usually caused by using the autotone and sometimes some other auto settings do that. Not that shutting it off will solve world hunger, because once you turn off the auto it might just fade out and you then have to go readjusts a bunch of other things. I have one graphite drawing and it washed out because one specific part of it is black and the rest is not-black, causing the scanner to overexpose the whole picture. I tried without auto, and it worked, but is very faded. I could never get it to contrast properly. I felt too much photoshop was just cheating. You just can't win with these things. I don't think the scanner model has anyhting to do with it unless it was a really cheap or 2nd hand scanner. HP, Canon, Epson, those are the best brands.. as long as it's less than 5 years old the only cure is to just fiddle with the settings and scan and rescan.
Somebody might know better. But in my experience scanners really suck when it comes to pencils.
I have gotten way better results by waiting for a nice day, laying traditional art on the floor outside in bright daylight and taking a photo. Even with a poopy camera phone it looks a 100 times better than on three different scanners after trying every option available.
Thanks for the suggestion. I'm going to try using a camera again (I used to for larger pieces beforehand) when I can get a hold of one. I'd try my phone, but it's very outdated and doesn't hold up well for photos.
Seriously though, from my experience pencil is slightly reflective and scanners use bright lights at close range. Whatever you do that combination always seems to result in a certain amount of detail being lost well before the stage where superior hardware or software processing can make a difference.
But like I say - somebody might know better and they are more than welcome to wade in with more detailed information!